Capteurs optiques minimalistes & réflexes oculomoteurs biomimétiques. Application à la robotique aérienne

• Kerhuel Lubin

Visual navigation in autonomous robots is usually based on video-cameras using several hundred thousands of pixels with sequential reading. Real time processing of such incoming data flows require major computing resources that would be hard to embed on a micro aerial vehicle of several grams or tens of grams. There already exist, however, lots of flying agents whose navigation performance in unknown environments is remarkable, even though they operate on a quite different basis. Birds and insects, in particular, show a unique ability to avoid obstacles and pursue preys or conspecifics. This amazing ability is due to their unique perception of the environment. Insects with their low cognitive abilities perceive their environment quite efficiently thanks to minimalist sensors. Some insects, like flies, improve their perception of the environment by stabilizing their visual system through de-coupling their head from the body and using an inertial reflex, similar to the mammalian “vestibulo-ocular reflex”. Stabilization of the “visual platform” is beneficial in that it simplifies the subsequent visual processing and enables efficient navigational strategies to be implemented. The first part of this work, dedicated to “visual sensors”, focuses on an elementary eye composed of only two photoreceptors (two pixels). We first improved the performance of a bio-inspired angular speed sensor, and revisited the working principle of the OSCAR sensor, both previously built at our laboratory. We then developed and constructed a new visual sensor, called VODKA, which allows the angular position of a contrasting edge or bar to be localized with utmost accuracy. In the second part, dedicated to visuo-inertial reflexes, we developed a micro aerial robot, called OSCAR II. Equipped with our visual sensors and an inertial sensor, OSCAR II, which weighs only 100 grams, is able to maintain its gaze locked onto a stationary target, and to pursue a moving target in yaw, even in the presence of strong aerial disturbances. With its added ability to perform eye saccades, OSCAR II bodes well for tomorrow's micro-aerial vehicles, whose heading will follow the gaze.